Double fuel burning stove

ABSTRACT

Double fuel burning stove formed by an external casing, characterised by the fact that said stove is composed of two hearths, a first hearth ( 4 ) for one fuel and a second hearth ( 5 ) for a second fuel, the second hearth ( 5 ) being placed above the first hearth ( 4 ) and the second hearth ( 5 ) is completely separated from the first hearth ( 4 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT Application No.PCT/IT2007/000503, filed Jul. 16, 2007, which claims benefit of ItalianApplication No. CZ2006A000019, filed Jul. 17, 2006.

TECHNICAL FIELD OF THE PATENT

The object of the present invention is a double fuel burning stove thatis capable of functioning with two different fuels, both with a solidfuel in pieces or logs such as wood and with a loose solid fuel such assawdust, wood pellets etc., and with gaseous fuel and liquid fuel.

STATE OF THE ART

Solid fuel fired stoves have been in use for a long time and, above allin those places near to woods, are frequently used because of theavailability of wood both in quantity and because of its low cost, andrepresent a form of heating that is widely used in these areas.

Recently, stoves using loose solid fuels such as sawdust, wood pellets,stones from olives or other dried fruits, olive residue etc. have beendeveloped. Loose solid fuel has, in respect to wood, the advantage ofbeing more easily transportable. Furthermore, a loose solid-fuel stovecan be automated and permits lighting and putting out the stove by atimer or by remote control.

Gas and liquid fuelled stoves have also been in use for a long time.

Bi-fuelled stoves are also present on the market, that have attempted tounite the advantages of a specific fuel with those of another fuel. Forexample, in order to unite the advantages of wood, above all itseconomy, to those of loose solid fuels, above all easy to handle, stoveshave been designed that can function with both fuels.

Patent DE3632023 describes a double fuel burning stove with two hearths.This stove presents, however, the inconvenience of having twocommunicating hearths and thus of having problems with the air flownecessary for combustion in the two hearths.

The patent Application FR-A-2745371 describes a coal and wood firedstove that can be transformed into a stove with a burner for liquid orgaseous fuels.

Patent EP 1427966 also describes a double fuel burning stove with twoburners, but it too has the disadvantage of having the two hearthscommunicating between themselves and thus of having problems with theflow of the air necessary for the combustion of the two hearths.

This disadvantage, present both in DE3632023 and in FR-A-2745371 and inEP 1427866, does not permit the simultaneous use of the two fuels or, ifit does permit their use, it does so with the loss of the quality of thecombustion since the air for the combustion of a fuel cannot be dosed ina specific way for that fuel; in general if two fuels need a differentdosing of the air for combustion then the air for combustion will bedosed in such a way that it is an average of the air for one fuel andfor that for the other fuel. In this way it will not be possible toobtain a high yield from the combustion.

The present invention proposes to overcome the difficulties anddisadvantages present in the solutions on sale at present.

The principal aim of the present invention is to create a double fuelburning stove formed by an external casing, characterised by the factthat said stove is composed of two hearths, a first hearth for one fueland a second hearth for a second fuel, the second hearth being placedabove the first hearth and the second hearth is completely separatedfrom the first hearth.

The principal characteristic of the invention is that of having a stovethat can function with two different fuels, for example wood that isreadily available in wooded areas and another fuel, for example pellets,that is easily handled. The wood fuel is fed by hand while the pelletscan be fed automatically.

The two fuels can be fed into one of the two hearths of the stovecontemporarily or into only one of the two, according to whichever ofthe fuels is more readily available or economically convenient or betteradapted at the moment of use. For example the stove can be broughtautomatically to the desired temperature with pellets when one is at adistance from it, while when one is near to the stove it can be fed withwood. The stove also permits the pellets to be fed automatically if forany reason the user does not feed the wood-fired hearth with thenecessary quantity of wood.

Another characteristic is given by the fact that both the first and thesecond fuels are solids and that one of the two fuels is a loose solidfuel.

Another characteristic is given by the fact that the first hearth has afirst flue and that the second hearth has a second flue and that saidflues are separated.

Another characteristic is given by the fact that both the first and thesecond hearths have separate aeration systems.

Another characteristic is given by the fact that a heat exchanger isplaced below the second hearth.

Another characteristic is given by the fact that the first hearth has afirst door and that the second hearth has a second door.

Another characteristic is given by the fact that the second hearth iscompletely separated from the first hearth by means of a double-walledbox that surrounds said second hearth.

Another characteristic is given by the fact that the double-walled boxthat surrounds said second hearth is present at least on the bottom andon three sides.

Another characteristic is given by the fact that the double-walled boxis a water-jacket.

Another characteristic is given by the fact that the heat exchangerpositioned below the second hearth is a heat exchanger for the heatingof the water.

Another characteristic is given by the fact that the double-walled boxis a heat exchanger for the heating of the air.

Another characteristic is given by the fact that the heat exchangerpositioned below the second hearth is an air heat exchanger.

Another characteristic is given by the fact that the first hearth is ahearth for wood and the second hearth is a hearth for loose solid fuel.

Another characteristic is given by the fact that the first hearth is ahearth for loose solid fuel and the second hearth is a hearth for wood.

Other characteristics and advantages of the invention will appear clearfrom the following description of some methods of creating theinvention, given as non-limiting examples in FIG. 1.

A BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 represents a section of the double fuel burning stove, object ofthe present invention.

DESCRIPTION OF THE INVENTION

In FIG. 1 a double fuel burning stove is represented, that is formed byan external casing 1, that can be of sheet-steel with a cavity space 2that separates an internal metal sheet 3 or which can be an externalsheet 1 insulated by refractory material or ceramic both internally andexternally.

The double fuel burning stove presents a first hearth 4 and a secondhearth 5. The second hearth 5 is placed above the first hearth 4. Thesecond hearth 5 is completely separated from the first hearth by meansof a double-walled box 6 that surrounds said second hearth 5 at least onthe bottom and on three sides. The first hearth 4 and the second hearth5 have separate flues, respectively the first hearth 4 has a first flue8 and the second hearth 5 has a second flue 9.

The smoke from the combustion in the first hearth 4 in passing to thefirst flue 8 brushes against and thus heats the external surface of thedouble-walled box 6, while the smoke from the combustion in the secondhearth 5 brushes against and thus heats the internal surfaces of thedouble-walled box 6.

The first hearth 4 has a first door 10 provided with a first handle 12,just as the second hearth 5 has a second door 11 provided with a secondhandle 13. Both the first hearth 4 and the second hearth 5 have separateaeration systems that are controlled externally, to increase or decreasethe air necessary for combustion, which for simplicity's sake are notshown.

Below the second hearth 5 a heat exchanger 14 is positioned, which hasthe double function of heating a fluid contained within it and ofprotecting the second hearth 5 from excessive heating from the effect ofthe flames that can arrive directly from the first hearth 4 positionedimmediately below it.

In the stove shown in FIG. 1 the stove is a double fuel burning stoveand presents the first hearth 4 that is fuelled by wood and the secondshearth 5 that is fuelled by a loose fuel (for example sawdust, woodpellets etc.). The second hearth 5 is positioned above the first hearth4. The double-walled box 6 is a water-jacket that surrounds the secondhearth 5 at least on the bottom and on three sides and separates itcompletely from the first hearth 4.

The water heated in the water-jacketed box 6 can be used for domesticheating and a heat exchanger for hot sanitary water 7 can be placed inthe water-jacket. The first hearth 4 and the second hearth 5 haveseparate flues (8 and 9). The smoke from the combustion in the firsthearth 4 in passing to the first flue 8 brushes against and thus heatsthe external surface of the water-jacketed box 6, while the smoke fromthe combustion in the second hearth 5 brushes against and thus heats theinternal surface of the water-jacketed box 6.

Both the first hearth 4 and the second hearth 5 have separate aerationsystems, externally controlled, to increase or decrease the airnecessary for combustion, which for simplicity's sake are not shown.

Below the second hearth 5 a heat exchanger 14 is positioned, and whichhas the double function of heating a fluid contained within it and ofprotecting the second hearth 5 from excessive heating caused by theflames that can arrive directly from the first hearth 4 positioneddirectly below it.

The stove can also be composed of the first hearth 4 for loose solidfuels placed in the lower part and of the second hearth 5, placed aboveit, for wood, but can also be composed of the first hearth for woodplaced in the lower part and of the second hearth, placed above it, forloose solid fuels.

Furthermore, the double-walled box 6 can be a water-jacket, or it can besubstituted by a heat exchanger for heating the air. The heat exchanger14 can function with water or it can be substituted by an air heatexchanger.

This invention is not limited to the representation given by the figuresbut can be perfected and modified by men expert in the art withoutaltering the aim of the patent.

This invention has numerous advantages and will permit to overcomeproblems which could not be achieved by heating systems on the markettoday.

1. Double fuel burning stove formed by an external casing, characterisedby the fact that said stove is composed of two hearths, a first hearth(4) for one fuel and a second hearth (5) for a second fuel, the secondhearth (5) being placed above the first hearth (4) and the second hearth(5) is completely separated from the first hearth (4).
 2. Double fuelburning stove according to claim 1 characterised by the fact that boththe first and the second fuels are solids and that one of the two fuelsis a loose solid fuel.
 3. Double fuel burning stove according to claim 1characterised by the fact that the first hearth (4) has a first flue (8)and that the second hearth (5) has a second flue (9) and that said fluesare separated.
 4. Double fuel burning stove according to claim 1characterised by the fact that both the first (4) and the second hearths(5) have separate aeration systems.
 5. Double fuel burning stoveaccording to claim 1 characterised by the fact that a heat exchanger(14) is placed below the second hearth (5).
 6. Double fuel burning stoveaccording to claim 1 characterised by the fact that the first hearth (4)has a first door (10) and that the second hearth (5) has a second door(11).
 7. Double fuel burning stove according to claim 1 characterised bythe fact that the second hearth is completely separated from the firsthearth (4) by means of a double-walled box (6) that surrounds saidsecond hearth (5).
 8. Double fuel burning stove according to claim 1characterised by the fact that the double-walled box (6) that surroundssaid second hearth (5) is present at least on the bottom and on threesides.
 9. Double fuel burning stove according to claim 1 characterisedby the fact that the double-walled box (6) is a water-jacket.
 10. Doublefuel burning stove according to claim 1 characterised by the fact thatthe heat exchanger (14) positioned below the second hearth (5) is a heatexchanger for the heating of the water.
 11. Double fuel burning stoveaccording to claim 1 characterised by the fact that the double-walledbox (6) is a heat exchanger for the heating of the air.
 12. Double fuelburning stove according to claim 1 characterised by the fact that theheat exchanger (14) positioned below the second hearth (5) is an airheat exchanger.
 13. Double fuel burning stove according to claim 1characterised by the fact that the first hearth (4) is a hearth for woodand the second hearth (5) is a hearth for loose solid fuel.
 14. Doublefuel burning stove according to claim 1 characterised by the fact thatthe first hearth (4) is a hearth for loose solid fuel and the secondhearth (5) is a hearth for wood.